Sprinter Van Electrical System: Solar Panel, Batteries, Fridge, Water Pump, Lights, Outlets
In this post, we'll go over the basics of our Sprinter Campervan Electrical System: the Solar Panel, our deep cycle batteries, 12v refrigerator, water pump, lights, and electrical outlets
Note: this post is about our first Sprinter Van, which we bought in May 2016, converted, lived/traveled in, and sold May 2018. If you are looking for info about our second Sprinter/current project, please check the dates of the post and make sure you're reading posts from 2018/2019. Cheers!
We should start out by saying that this was probably one of the most frustrating aspects of our build. Cade spent a lot of time reading up on wiring and electrical systems, and still made a few mistakes. If you don’t have experience, you may want to consult with an electrician to help you with your conversion. Especially if you plan to use solar panels, someone who is knowledgeable about solar electric systems can make this way more straightforward for you. If you’re planning on doing it on your own, please realize that we are not experts by any means and this post will only serve as a basic guide for the major components we used.
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To determine what type of electrical system you need it is best to figure out what you are going to be using, how much power you need to run everything, and work backwards from there. We knew from the beginning that we wouldn’t need a crazy amount of power. We made a list of the things that would use power in our van:
Overhead Fan/ Roof Vent
The fridge is by far the biggest power user of these, and since we chose a relatively efficient top-loading model even that shouldn’t use much. The other major consumer would be the equipment we would plug in to charge: camera batteries, gopros, laptops, etc. We don’t need anything crazy like a microwave or blender and our stove and oven run on propane. We knew we wanted to use solar to power our electrical system. Using free energy from the sun is obviously the most sustainable choice--we spend most of our time in sunny climates and love being off the grid.
Since our power needs are relatively small, we decided to keep the system as simple as possible. Goal Zero makes a solar ‘generator’ called the Yeti 1250 that combines a 100ah AGM battery, a charge controller, system monitor, and 110v inverter. We decided to use this as the basis of our electrical system. It is a bit more expensive than buying the components individually but saves a huge amount of time and hassle wiring each component together. One thing to keep in mind is that with the Yeti you are limited slightly-- both with how much solar you can put in, and with how much power you can draw through the 110v inverter. For our needs it performs well, but if you want to run more than 300w of solar, or use an appliance that eats more than 1200w through the 110v outlets (like a Vitamix or an iron), you should piece together your own heavy duty set- up.
We wanted to have a bit more storage than the Yeti provides alone (100ah). The Yeti is designed so it can be piggybacked to another battery, so expanding the storage is relatively straightforward. Some Sprinters come with an auxiliary battery under the hood. Ours did not, but we decided another 100ah would be good for our needs. We also wanted the ability to charge the Yeti’s battery and auxiliary battery from the van’s alternator while driving. There are a number of different ways to do this through Mercedes OEM or aftermarket products. After some deliberation, we decided to use the Mercedes parts made for the van. We ordered (from our local Mercedes dealer) the factory auxiliary battery and tray for mounting under the hood as well as the Mercedes charge relay that connects the starter battery to the auxiliary batteries when the car is running. It was a bit of a maze wiring it all together; the starter battery is under the driver’s side floor boards, the auxiliary battery is under the hood, the charge relay is installed under the driver seat, and our Yeti is halfway back through the cargo area of the van. When hooking batteries together it is important that you use batteries of the same type. Fortunately one of the available Mercedes batteries is a 100ah AGM, which is the same type as the Yeti. Ideally you want them as close to each other as possible. Ours are about 10 feet apart.
Fuse box, outlets, lights, etc
We used a 150A mega fuse in a simple housing at the junction between the Yeti and the auxiliary battery. We used this housing to tie in another wire to a Blue Sea Systems Fuse Block (located in our bedside cabinet) to distribute power to our 12v components: the lights and light switches, water pump, ceiling fan, and USB outlets. For the 110v outlets we used an extension cord plugged directly into the Yeti’s outlet, then ran it through the walls, cut the end, and wired it into normal house outlets.
For lights we installed 4 overhead LED lights and one under-cabinet dimming light bar over the countertop/sink area. In addition, we installed 2 of the same overhead lights in the gear storage area under the bed so we can see better when digging around for something in the dark. These are operated by a separate switch near the rear door. We also ended up getting a string of LED Christmas lights like these and hung them around the perimeter of the van (they plug in to an outlet near the rear door). These provide the nicest ambient lighting of all our options, so we end up using them the most when we’re hanging out at night. We love the vibe and call them our 'party lights.' The overhead lights turned out pretty bright. They are very functional, but a little too bright for mood lighting. If we could do it over again, we would plan better for a dimmer on the overhead lights. We also have a couple small portable lights like this lantern and this one that we use when cooking outside or sitting at a picnic table or away from the van.
Note: It should also be noted that LED lights must be wired in parallel (not a series). We neglected to do this originally, then had to figure out a way to make our series into a parallel after we already had our wallpaper installed. It ended up working out, but it would have saved us a huge headache (and some fun Macgyver-ing) to do it right the first time. Hence the recommendation to talk to an electrician if you don’t have experience with this sort of thing. Oops.
Most of the other assorted electrical supplies that we used came from the local hardware store.
Note: We mentioned this in our post about insulation and rough wiring, but we should say again that if we could do it all over again we would run conduit before paneling the interior of the van so that we could make changes down the road. We learned the hard way (after our walls, wallpaper and lights were installed) how difficult it is to make changes without conduit!
We decided to use one big solar panel on the roof of our van instead of multiple small ones. Grape Solar was having a sale on their 265w panels, which fit perfectly on the roof, so we went with one of those. We mounted the panel under our Rhino Rack roof crossbars using angle aluminum, these specialized brackets, and some track sliders from EuroCampers.com. We used the threaded track sliders and the channel on the bottom side of the crossbars to essentially hang the solar panel from the bars. Unfortunately this means that we had to cover up a small strip of the panel with one of the crossbars--you lose some efficiency when shading even the small portion of the panel. But we really wanted to be able to use the roof rack for our paddleboards and other gear, so went that route anyway. If we had more space we could have under-mounted it without having to cover any of the panel, but we were limited by our roof vent. We drilled a hole in the roof for the wires from the panel to pass through to the interior of the van (see our post on installing the fan and pass through for more info). The cable from the panel plugs right into the front of the Yeti with an MC4 adapter cable.
Overhead Fan/ Roof Vent
We found two main choices for non A/C roof vents: the Maxxfan and Fan-tastic fans. They both come in multiple models with features like power or manual opening, multiple speed settings, two different modes so it can be used like a ceiling fan or an exhaust fan, auto rain sensing, thermostat control so you can set it to come on automatically when the inside temp gets too hot, and remote control so you can turn it off without reaching above your head. We ended up going with this MaxxFan mostly because the vent can stay open with the fan running in the rain. The vent hood is also a bit lower-profile on the roof. This originally wasn’t something we were paying attention to, but after carrying our paddleboards on the roof rack a few times, it turned out to be really advantageous.
We opted for a large budget fridge. It's a dual zone model, so you can set both sides to be a fridge and/or freezer. We've never felt the need for a freezer in the van, and would rather use all the space for refrigerating, so probably could have gone with a single zone instead. The more expensive options like Engel, ARB, Dometic, and National Luna all use a more efficient compressor, so they use less power. We might be upgrading as soon as we have the budget. This one has worked great for us all summer. The only downfall is it is a bit more power hungry than its competitors. We only really noticed an issue with extended periods of cloudy weather and once we started going into shorter daylight hours (winter). The fridge plugs into the 12v outlet on the Yeti itself. *2018 Update: we did indeed upgrade to a Dometic fridge, which we find more efficient and also has more usable space inside.
We used a Shurflo water pump and mounted it to the cabinet wall under the sink. From our research, the Shurflos seem to have the best reviews, and you can run them dry without damage. We put it on a separate switch inside the cabinet, so we can turn it on only when we’re running the water. It’s been great for us so far. When it’s actively pumping water or building up pressure it does make a funny noise, but that’s pretty standard for any RV-style pump. We did consider getting a foot or hand pump style sink, but couldn’t find any that got great reviews. The pump draws barely any power, especially for the small amount we use it, so we haven’t had any issues. We also frequently use our Pressure Shower for dishes instead, so we get the best of both worlds. We'll have more info about plumbing and our water system in a future post.
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